Solid-state electrolyte membrane, method for producing the same, and battery

Abstract

The application discloses a kind of solid electrolyte membrane and its preparation method and battery, belong to lithium battery technical field, solid electrolyte membrane includes lithium vanadate salt and binder, the mass ratio of the lithium vanadate salt and the binder is 100: (0.5~100).Novel solid electrolyte material provided by the application can be prepared into film by two kinds of preparation methods of dry method and wet method, production operation is simple and low in cost, the solid electrolyte prepared is not sensitive to air, ion conductivity is high and electrochemical stability window is wider, can realize large-scale processing production of solid electrolyte in air environment, and speed up the industrialization of solid-state battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a solid electrolyte membrane, its preparation method, and a battery. Background Technology

[0002] Lithium-ion batteries have been widely used in energy storage and electric vehicles due to their high energy density and long cycle life. However, the organic electrolytes used in traditional liquid lithium-ion batteries pose risks of leakage and flammability, and are prone to thermal runaway under abuse, severely limiting their further application. In solid-state battery systems, solid electrolytes replace separators and liquid electrolytes, fundamentally eliminating the safety risks associated with electrolytes while meeting the requirements of high energy density and safety, thus making them a key focus of next-generation energy storage technology.

[0003] Solid electrolytes are key materials in solid-state batteries, and their properties directly determine the overall performance of the battery. Currently, the mainstream solid electrolytes include sulfides, oxides, halides, and polymers: Sulfides have high ionic conductivity, but are extremely sensitive to air, have strict requirements for the production environment, and have high costs for key raw materials, and also require high external pressure to optimize interfacial contact; Oxides have good air stability, but the materials themselves are brittle and have poor interfacial contact; Halides have controllable costs, but their chemical stability still needs improvement; Polymers have strong processability and good interfacial contact, but have low room temperature ionic conductivity and transport number.

[0004] To address key issues in various solid-state electrolyte systems, researchers have proposed a series of optimization and improvement methods. For the air stability of sulfides, elemental doping (CN116404241A) and inter-doping (CN116613372A) have been proposed; for the interfacial contact problem of oxides, surface coating (CN111509293A) and system compositing (CN114649586A) have been proposed; for the chemical stability of halides, high entropy (CN115332618A) has been proposed; and for the ionic conductivity of polymers, functional group modification (CN112898569A) and crosslinking (CN107069081A) have been proposed. While these methods have shown effectiveness in addressing specific system problems, they complicate the preparation process, hindering the simplification of process flows and the control of production costs.

[0005] Based on the above problems, there is an urgent need to develop a new type of solid electrolyte that is low in cost, simple in process, insensitive to air, has high ionic conductivity, and a wide electrochemical stability window, so as to realize the large-scale processing and production of solid electrolytes in the air environment and accelerate the industrialization of solid batteries. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a solid electrolyte membrane, its preparation method, and a battery thereof. The process provided by this invention is simple and the materials are inexpensive. The prepared solid electrolyte membrane exhibits high ionic conductivity and a wide electrochemical stability window, demonstrating good application prospects and practical value.

[0007] This invention provides the following technical solution: In a first aspect, a solid electrolyte membrane is provided, comprising lithium vanadate and a binder, wherein the mass ratio of the lithium vanadate to the binder is 100:(0.5~100).

[0008] Furthermore, the lithium vanadate salt includes any one of LiVO3, Li3VO4, LiV3O8, LixV2O5 (0<X≤3), LiVO2, or modified lithium vanadate salts thereof.

[0009] Furthermore, the adhesive includes any one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, polytetrafluoroethylene, polyethylene oxide, polyacrylonitrile, polycarbonate, polysiloxane, polyphosphazene, or polyvinyl chloride.

[0010] Furthermore, the modification method used for the modified lithium vanadate salt includes either doping or coating modification. The doping elements used in the doping modification include any one or more of sodium, iron, manganese, cobalt, nickel, magnesium, calcium, copper, zinc, titanium, and aluminum. The coating materials used in the coating modification include any one or more of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, chromium oxide, or lithium nitride.

[0011] Furthermore, the mass ratio of the doping element to the lithium vanadate salt is (0.5~10):100.

[0012] Furthermore, the mass ratio of the coating material to the lithium vanadate salt is (0.5~10):100.

[0013] In the above technical solutions, doping can broaden the lithium-ion transport channels inside the lattice and reduce the lithium-ion migration energy barrier, while coating can accelerate lithium-ion transport at the interface. Both methods can further improve the ionic conductivity of the solid electrolyte membrane provided by the present invention.

[0014] Furthermore, the particle size of the lithium vanadate salt is 1 nm to 10 μm, preferably 10 nm to 100 nm.

[0015] Furthermore, the thickness of the solid electrolyte membrane is 1~300 μm, preferably 10 μm~100 μm.

[0016] In the above technical solutions, the size of the lithium vanadate salt and the thickness of the solid electrolyte membrane affect the self-support and ionic conductivity of the electrolyte. Therefore, lithium vanadate salt with a particle size of 10~100 nm and a solid electrolyte membrane with a thickness of 10~100 µm are selected as the preferred conditions for implementing the present invention, in order to further verify the feasibility of the method of the present invention.

[0017] In a second aspect, a method for preparing a solid electrolyte membrane according to any one of the first aspects is provided, including either a dry method or a wet method; The dry method includes the following steps: Lithium vanadate salt and binder are mixed and stirred until homogeneous to obtain a premixed material; The premixed material is fully sheared to obtain a fibrous premixed material; The fibrous premixed material is rolled to obtain a solid electrolyte membrane.

[0018] Furthermore, the wet process includes the following steps: Dissolve the adhesive in an organic solvent and stir thoroughly until homogeneous to obtain an adhesive slurry; Lithium vanadate salt is added to the binder slurry and stirred thoroughly to obtain an electrolyte slurry; The electrolyte slurry is poured onto the substrate, coated and vacuum dried to obtain a solid electrolyte membrane.

[0019] Further, the lithium vanadate salt and the binder are mixed and stirred for 10-60 min.

[0020] Furthermore, the premixed material is sheared at 50~80°C at a shearing speed of 10000~15000 r / min.

[0021] Furthermore, the specific surface area of ​​the fibrous premixed material is 10-20% of that of the premixed material.

[0022] In the above technical solution, high-speed shearing of the premixed material in the dry process can fibrose the binder in the premixed material, which improves the self-support of lithium vanadate when combined with lithium vanadate, making it easier to form a film independently.

[0023] Furthermore, the fibrous premixed material is subjected to repeated hot rolling treatment by a roller press, with a rolling speed of 3~10 mm / s and a rolling temperature of 50~80℃. The thickness reduction ratio of each rolling is 10~20%.

[0024] Furthermore, the adhesive is dissolved in an organic solvent and stirred at a stirring speed of 300~1000 r / min, a stirring temperature of 25~80℃, and a stirring time of 6~24 h.

[0025] Furthermore, the lithium vanadate salt is added to the binder slurry and stirred at a stirring speed of 300~1000 r / min, a stirring temperature of 25~80℃, and a stirring time of 6~24 h.

[0026] Furthermore, the electrolyte slurry is poured onto the substrate, coated with a 50-1000 μm layer, and vacuum dried at 60-80°C for 6-24 h to obtain a solid electrolyte membrane.

[0027] Thirdly, a battery is provided, comprising a positive electrode, a negative electrode, and a solid electrolyte membrane as described in any one of the first aspects or a solid electrolyte membrane prepared using the method for preparing a solid electrolyte membrane as described in any one of the second aspects.

[0028] Furthermore, the positive electrode includes any one of lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based oxide, vanadium pentoxide, lithium vanadate, or lithium titanate. The negative electrode includes any one of lithium metal or lithium alloy.

[0029] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention uses lithium vanadate combined with polymer binder to prepare solid electrolyte membrane. As a fast ion conductor, lithium vanadate has a wide electrochemical stability window, high ionic conductivity and transport number, which can reduce the ion transport energy barrier and ensure the rapid transport of ions in solid electrolyte. Its high air stability can ensure the stability of solid electrolyte membrane in air. The polymer as binder can improve the self-support of lithium vanadate, facilitate independent film formation, and further improve the processability of solid electrolyte membrane. (2) The solid electrolyte membrane provided by the present invention can solve the interface problems of high voltage stability of solid electrolyte positive electrode and lithium dendrite growth of negative electrode, and has a wide electrochemical stability window. The lithium vanadate salt as the main body can ensure the mechanical strength of the electrolyte, reduce the risk of dendrite puncture, and improve battery safety and stability. (3) In view of the problem that existing solid electrolyte materials are sensitive to air, the solid electrolyte membrane provided by the present invention is applicable to both dry and wet preparation processes. The high air stability and self-supporting characteristics of the solid electrolyte membrane can be used in existing processing and production equipment, enabling mass production in an air environment. The preparation process is simple and the production cost is low, which has good application prospects and practical value. Attached Figure Description

[0030] Figure 1 This is an image of the solid electrolyte membrane in Embodiment 1 of the present invention; Figure 2 Impedance diagrams of SS / SS symmetric cells with solid electrolyte membranes in Embodiment 1 and Comparative Example 1 of the present invention; Figure 3 This refers to the electrochemical stability window of the Li / SS battery with a solid electrolyte membrane in Example 1 and Comparative Example 1 of the present invention. Figure 4 This is a graph showing the change in ionic conductivity of the solid electrolyte membranes in Example 1 and Comparative Example 1 of the present invention after being exposed to air for different numbers of days; Figure 5 This is a comparison chart of the rate performance of Li / LFP full cells with solid electrolyte membranes in Example 1 and Comparative Example 1 of the present invention. Figure 6 Impedance diagram of the SS / SS symmetrical cell of the solid electrolyte membrane in Embodiment 4 of the present invention; Figure 7 This is a cycling performance diagram of a Li / LFP full cell with a solid electrolyte membrane in Example 4 of the present invention. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0032] In the description of this invention, unless otherwise stated, "a plurality of" means two or more. The terms "comprising," "including," "having," "containing," etc., as used herein are open-ended, meaning they include but are not limited to.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Example 1

[0036] Li3VO4 with a particle size of about 100 nm and polytetrafluoroethylene were added to a mortar at a mass ratio of 10:1 and stirred at room temperature for 10 min to obtain a premixed material.

[0037] The premixed material was subjected to high-speed shearing at 60°C at a speed of 12,000 r / min to fiberize the binder. The specific surface area of ​​the material after high-speed shearing was 10-20% of that of the premixed material.

[0038] The fibrous material was subjected to repeated hot rolling treatment by a roller press at a speed of 5 mm / s and a temperature of 60 ℃. The thickness was reduced by 10~20% with each rolling, and the thickness was gradually reduced to 30 μm to obtain a dry-prepared solid electrolyte membrane, denoted as DL4.

[0039] Depend on Figure 1 As shown, the solid electrolyte membrane prepared by the dry method has a smooth and flat surface, uniform color, and self-supporting properties, making it suitable for large-scale processing and production.

[0040] Example 2

[0041] Na-doped Li with a particle size of approximately 100 nm and an elemental stoichiometric ratio of Na:Li = 0.1:2.9 2.9 Na 0.1 VO4 and polytetrafluoroethylene were added to a mortar at a mass ratio of 10:1 and dry-mixed at room temperature for 10 min to obtain a premixed material.

[0042] The premixed material was subjected to high-speed shearing at 60°C at a speed of 12,000 r / min to fiberize the binder. The specific surface area of ​​the material after high-speed shearing was 10-20% of that of the premixed material.

[0043] The fiberized material was subjected to repeated hot rolling treatment by a roller press at a rolling speed of 5 mm / s and a rolling temperature of 60℃. The thickness was reduced by 10-20% with each rolling process, and the thickness was gradually reduced to 30 μm to obtain a dry-prepared solid electrolyte membrane, denoted as DLN4.

[0044] Example 3

[0045] Alumina-coated Li3VO4 with a particle size of approximately 200 nm and a mass percentage of 0.5% and polytetrafluoroethylene were added to a mortar at a mass ratio of 10:1 and dry-mixed at room temperature for 10 min to obtain a premixed material.

[0046] The premixed material was subjected to high-speed shearing at 60 °C at a speed of 12000 r / min to fiberize the binder. The specific surface area of ​​the material after high-speed shearing was 10-20% of that of the premixed material.

[0047] The fibrous material was subjected to repeated hot rolling treatment by a roller press at a rolling speed of 5 mm / s and a rolling temperature of 60 ℃. The thickness was reduced by 10~20% each time the material was rolled, and the thickness was gradually reduced to 30 μm to obtain a dry-prepared solid electrolyte membrane, denoted as DLA4.

[0048] Example 4

[0049] 300 mg of polyvinylidene fluoride was dissolved in 3 ml of N-methylpyrrolidone and magnetically stirred at 60 °C for 24 h until completely dissolved. The stirring speed was 500 r / min to obtain the adhesive slurry.

[0050] 300 mg of LiV3O8 with a particle size of about 100 nm was added to the polymer binder slurry, and the mixture was magnetically stirred at 500 r / min for 24 h at 60 °C and ultrasonically dispersed for 2 h to obtain the electrolyte slurry.

[0051] The electrolyte slurry was poured onto a glass plate, coated with a 250 μm doctor blade, and vacuum dried at 60℃ for 24 h to obtain a solid electrolyte membrane with a thickness of 100 μm, denoted as WL8.

[0052] Example 5

[0053] 300 mg of polyvinylidene fluoride was dissolved in 3 ml of N-methylpyrrolidone and magnetically stirred at 60 °C for 24 h until completely dissolved. The stirring speed was 500 r / min to obtain the adhesive slurry.

[0054] 300 mg of LiVO2 with a particle size of about 50 nm was added to the binder slurry, and the mixture was magnetically stirred at 500 r / min at 60 °C for 24 h and ultrasonically dispersed for 2 h to obtain the electrolyte slurry.

[0055] The electrolyte slurry was poured onto a glass plate, coated with a 250 μm doctor blade, and vacuum dried at 60℃ for 24 h to obtain a solid electrolyte membrane with a thickness of 100 μm, denoted as WL2.

[0056] Example 6

[0057] 300 mg of polyvinylidene fluoride was dissolved in 3 ml of N-methylpyrrolidone and magnetically stirred at 60 °C for 24 h until completely dissolved. The stirring speed was 500 r / min to obtain the polymer adhesive slurry.

[0058] 300 mg of Li with a particle size of approximately 50 nm was used. 0.35 V2O5 was added to the binder slurry, and the mixture was magnetically stirred at 500 r / min for 24 h at 60℃, followed by ultrasonic dispersion for 2 h to obtain the electrolyte slurry.

[0059] The electrolyte slurry was poured onto a glass plate, coated with a 150 μm doctor blade, and vacuum dried at 60℃ for 24 h to obtain a solid electrolyte membrane with a thickness of 50 μm, denoted as WL5.

[0060] Example 7

[0061] 300 mg of polyvinylidene fluoride was dissolved in 3 ml of N-methylpyrrolidone and magnetically stirred at 60 °C for 24 h until completely dissolved. The stirring speed was 500 r / min to obtain the adhesive slurry.

[0062] 300 mg of Li3VO4 with a particle size of about 100 nm was added to the binder slurry, and the mixture was magnetically stirred at 500 r / min for 24 h at 60 °C and ultrasonically dispersed for 2 h to obtain the electrolyte slurry.

[0063] The electrolyte slurry was poured onto a glass plate, coated with a 150 μm doctor blade, and vacuum dried at 60℃ for 24 h to obtain a solid electrolyte membrane with a thickness of 50 μm, denoted as WL4.

[0064] Example 8

[0065] 300 mg of polyvinylidene fluoride was dissolved in 3 ml of N-methylpyrrolidone and magnetically stirred at 60 °C for 24 h until completely dissolved. The stirring speed was 500 r / min to obtain the adhesive slurry.

[0066] 400 mg of Li with a particle size of approximately 100 nm 2.9 Na 0.1 VO4 was added to the binder slurry, and the mixture was magnetically stirred at 500 r / min for 24 h at 60℃, followed by ultrasonic dispersion for 2 h to obtain the electrolyte slurry.

[0067] The electrolyte slurry was poured onto a glass plate, coated with a 150 μm doctor blade, and vacuum dried at 60℃ for 24 h to obtain a solid electrolyte membrane with a thickness of 50 μm, denoted as WLN4.

[0068] Example 9

[0069] Dissolve 300 mg of polyvinylidene fluoride in 3 ml of N-methylpyrrolidone, and stir magnetically at 60 °C for 24 h until completely dissolved. The stirring speed is 500 r / min to obtain the adhesive slurry.

[0070] 400 mg of alumina-coated Li3VO4 with a particle size of about 200 nm was added to the binder slurry, and the mixture was magnetically stirred at 500 r / min for 24 h at 60 °C and ultrasonically dispersed for 2 h to obtain the electrolyte slurry.

[0071] The electrolyte slurry was poured onto a glass plate, coated with a 150 μm doctor blade, and vacuum dried at 60℃ for 24 h to obtain a solid electrolyte membrane with a thickness of 50 μm, denoted as WLA4.

[0072] Comparative Example 1

[0073] 300 mg of polyvinylidene fluoride (PVDF) and 200 mg of lithium difluorosulfonylimide were dissolved in 3 ml of N-methylpyrrolidone. The mixture was magnetically stirred at 60 °C for 24 h until completely dissolved, with a stirring speed of 500 r / min, to obtain a polymer electrolyte slurry. The polymer electrolyte slurry was cast onto a glass plate, coated with a 150 μm doctor blade, and vacuum dried at 60 °C for 24 h to obtain a 50 μm thick polymer solid electrolyte membrane, denoted as PVDF.

[0074] Comparative Example 2

[0075] 300 mg of polyvinylidene fluoride-hexafluoropropylene and 300 mg of lithium bis(trifluoromethanesulfonyl)imide were dissolved in 3 ml of N-methylpyrrolidone. The mixture was magnetically stirred at 60 °C for 24 h until completely dissolved, with a stirring speed of 500 r / min, to obtain a polymer electrolyte slurry. The polymer electrolyte slurry was cast onto a glass plate, coated with a 150 μm doctor blade, and vacuum dried at 60 °C for 24 h to obtain a polymer solid electrolyte membrane with a thickness of 50 μm, denoted as PVDF-HFP.

[0076] Application Example 1

[0077] The solid electrolyte membranes prepared in Examples 1-9 and Comparative Examples 1-2 were used to form SS / SS coin cells with two stainless steel discs (SS). AC impedance spectroscopy was performed at 25°C using a CHI660E electrochemical workstation from Shanghai Chenhua, with the test frequency band being 10 GHz. 6 The ionic conductivity of the solid electrolyte was calculated using impedance spectroscopy information at a frequency of ~0.1 Hz and a voltage of 10 mV, and the results are shown in Table 1.

[0078] Table 1 shows the ionic conductivity test results of each embodiment at 25°C.

[0079] As can be seen from Table 1, the ionic conductivity of the solid electrolytes prepared in Examples 1-9 is significantly higher than that in Comparative Examples 1-2, indicating that lithium vanadate salt materials are more conducive to ion transport than polymer solid electrolytes.

[0080] The solid electrolyte membranes prepared in Examples 1-9 and Comparative Examples 1-2 were combined with lithium metal anode (Li) and lithium iron phosphate cathode (LFP) to form Li / LFP coin cells. The long-cycle performance of the Li / LFP full cells was tested using the CT-4008T battery testing system of Shenzhen Xinwei. The voltage range was 2.5-4 V, the rate was 0.5 C, and the test temperature was 25℃. The results are shown in Table 2.

[0081] Table 2 compares the long-cycle performance of the Li / LFP full cells of each embodiment and comparative example.

[0082] As can be seen from Table 2, the Li / LFP full cells prepared with solid electrolytes in Examples 1-9 exhibited significantly higher discharge specific capacity and capacity retention than those in Comparative Examples 1-2, indicating that the solid electrolyte based on lithium vanadate has better cycle stability in lithium metal battery systems than existing solid electrolyte systems.

[0083] Application Example 2

[0084] Based on the dry preparation process, this application example takes Example 1 and Comparative Example 1 as examples to further explore the electrochemical stability and rate performance of the solid electrolyte membrane prepared by the dry process in the battery.

[0085] like Figure 2 As shown, Example 1 and Comparative Example 1 were used as solid electrolytes to assemble SS / SS symmetric cells, and their AC impedance was tested under the same conditions as those provided in Application Example 1. Figure 3 As shown, the electrochemical stability window of the Li / SS batteries assembled using Example 1 and Comparative Example 1 as solid electrolytes was tested using linear sweep voltammetry. The scan range was 2–5 V, and the scan rate was 1 mV / s. Figure 2 and Figure 3 It can be seen that the solid electrolyte membrane prepared in Example 1 has extremely low ion conduction resistance and a wide electrochemical stability window of 2~4.6V, while Comparative Example 1 has already started to undergo oxidation reaction at 4.2V, proving that the solid electrolyte provided by the present invention has excellent ion conduction performance and electrochemical stability on the positive electrode side.

[0086] like Figure 4As shown, the SS / SS symmetric cells assembled using solid electrolyte membranes in Examples 1 and 1 were exposed to air for different numbers of days, and the changes in their ionic conductivity over time were tested. The test conditions were consistent with those provided in Application Example 1. Figure 4 It can be seen that after being exposed to air for 5 days, the solid electrolyte membrane DL4 provided in Example 1 can still maintain a high ionic conductivity close to that of the initial state, while Comparative Example 1 almost loses its ionic conductivity, proving the possibility of large-scale processing and production of the solid electrolyte membrane provided by the present invention under air conditions.

[0087] like Figure 5 As shown, Li / LFP coin cells assembled using Example 1 and Comparative Example 1 as solid electrolyte membranes were tested, and their rate performance was obtained. The rate test range was 0.2~5 C, and the voltage range was 2.5~4 V. From Figure 5 As can be seen, the Li / LFP full cell assembled with the solid electrolyte prepared in Example 1 exhibits excellent rate performance, maintaining a high discharge specific capacity of 86.7 mAh / g at a 5 C rate, which is significantly better than that of Comparative Example 1, demonstrating the fast ion conduction capability and interface stability of the solid electrolyte membrane provided by the present invention.

[0088] Application Example 3

[0089] Based on the wet preparation process, this application example takes the electrolyte membrane WL8 prepared in Example 4 as an example to further explore the ionic conductivity and cycle performance of the solid electrolyte membrane prepared by the wet preparation process in the battery.

[0090] like Figure 6 As shown, the solid electrolyte membrane WL8 prepared in Example 4 was assembled into an SS / SS symmetric cell, and its AC impedance test diagram was obtained. The test conditions were the same as those provided in Application Example 1. Figure 6 It can be seen that the solid electrolyte prepared in Example 4 has extremely low ion conduction resistance, proving that the solid electrolyte prepared by the wet process can also meet the ion conduction requirements of solid electrolytes.

[0091] like Figure 7 As shown, the solid electrolyte membrane prepared in Example 4 was assembled into a Li / LFP coin cell, and its cycle performance was tested. The voltage range was 2.5~4 V, and the rate of change was 0.5 C. Figure 7 It can be seen that the Li / LFP full cell with WL8 as the solid electrolyte membrane has excellent cycle performance, with a high discharge specific capacity of 147.9 mAh / g and almost no decay after 50 cycles, which proves that it has good interface stability in lithium metal battery system and can avoid coulombic efficiency and capacity decay caused by dendrite growth.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A solid electrolyte membrane, characterized in that, It includes lithium vanadate and a binder, wherein the mass ratio of the lithium vanadate to the binder is 100:(0.5~100).

2. The solid electrolyte membrane according to claim 1, characterized in that, The lithium vanadate salt includes LiVO3, Li3VO4, LiV3O8, and Li x V2O5 (0 < X ​​≤ 3), LiVO2, or any one of its modified lithium vanadate salts; And / or, the adhesive comprises any one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, polytetrafluoroethylene, polyethylene oxide, polyacrylonitrile, polycarbonate, polysiloxane, polyphosphazene, or polyvinyl chloride.

3. The solid electrolyte membrane according to claim 2, characterized in that, The modification method used for the modified lithium vanadate salt includes either doping or coating modification. The doping elements used in the doping modification include any one or more of sodium, iron, manganese, cobalt, nickel, magnesium, calcium, copper, zinc, titanium, and aluminum. The coating materials used in the coating modification include any one or more of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, chromium oxide, or lithium nitride.

4. The solid electrolyte membrane according to claim 3, characterized in that, The mass ratio of the doping element to the lithium vanadate salt is (0.5~10):100; And / or, the mass ratio of the coating material to the lithium vanadate salt is (0.5~10):

100.

5. The solid electrolyte membrane according to claim 1, characterized in that, The particle size of the lithium vanadate salt is 1 nm to 10 μm; And / or, the thickness of the solid electrolyte membrane is 1~300 μm.

6. A method for preparing a solid electrolyte membrane according to any one of claims 1 to 5, characterized in that, This includes either the dry method or the wet method; The dry method includes the following steps: Lithium vanadate salt and binder are mixed and stirred until homogeneous to obtain a premixed material; The premixed material is fully sheared to obtain a fibrous premixed material; The fibrous premixed material is rolled to obtain a solid electrolyte membrane; And / or, the wet process includes the following steps: Dissolve the adhesive in an organic solvent and stir thoroughly until homogeneous to obtain an adhesive slurry; Lithium vanadate salt is added to the binder slurry and stirred thoroughly to obtain an electrolyte slurry; The electrolyte slurry is poured onto the substrate, coated and vacuum dried to obtain a solid electrolyte membrane.

7. The method for preparing a solid electrolyte membrane according to claim 6, characterized in that, Mix the lithium vanadate salt and the binder for 10-60 min; And / or, the premixed material is sheared at 50~80°C at a shearing rate of 10000~15000 r / min; And / or, the specific surface area of ​​the fibrous premixed material is 10-20% of that of the premixed material; And / or, the fibrous premixed material is subjected to repeated hot rolling treatment by a roller press, with a rolling speed of 3~10mm / s, a rolling temperature of 50~80℃, and a thickness reduction ratio of 10~20% for each rolling.

8. The solid electrolyte membrane according to claim 6, characterized in that, The adhesive is dissolved in an organic solvent and stirred at a stirring speed of 300-1000 r / min, a stirring temperature of 25-80℃, and a stirring time of 6-24 h. And / or, the lithium vanadate salt is added to the binder slurry and stirred at a stirring speed of 300~1000 r / min, a stirring temperature of 25~80℃, and a stirring time of 6~24 h; And / or, the electrolyte slurry is cast onto a substrate, coated with a 50-1000 μm layer by scraping, and vacuum dried at 60-80°C for 6-24 h to obtain a solid electrolyte membrane.

9. A battery, characterized in that, It includes a positive electrode, a negative electrode, and a solid electrolyte membrane as described in any one of claims 1 to 5, or a solid electrolyte membrane prepared by the method described in any one of claims 6 to 8.

10. The battery according to claim 9, characterized in that, The positive electrode includes any one of lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based oxide, vanadium pentoxide, lithium vanadate, or lithium titanate. The negative electrode includes any one of lithium metal or lithium alloy.

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